The present invention relates generally to the field of liquid containment devices. More particularly, the present invention relates to a device for containing residue drained from a still utilized in photopolymer solvent recovery operations.
It is known in the prior art to produce printing plates from acrylic elastomer resins and synthetic rubbers utilizing photoengraving and chemical milling techniques. Generally, a layer of such resins or rubbers are placed onto a surface of a flexible plate and then exposed to light through a photographic film or stencil having a desired pattern to be formed onto the printing plate. Exposure of the resins and rubbers to light cures the resins and rubbers, altering the susceptibility of the resins and rubbers to removal by a photopolymer solvent. By applying the photopolymer solvent to the light exposed layer of resins or rubbers on the printing plate, the uncured photopolymer resin or rubber is chemically etched away by the photopolymer solvent in a pattern reverse to that of the film or stencil. The resin or rubber etched from the plate is removed with the waste photopolymer fluid.
Typically, the solvents utilized for the photopolymer solvent are relatively costly and generally have flash point temperatures above 140xc2x0 F. Further, disposal of the waste photopolymer fluid is likewise relatively expensive and presents environmental problems and concerns. Therefore, to more efficiently produce the aforementioned printing plates, devices were developed to recover the photopolymer solvent from the waste photopolymer fluid.
Prior art photopolymer solvent recovery devices utilize vacuum assisted distillation to separate the photopolymer solvent from the photopolymer resins or rubbers. Upon separation and removal of the photopolymer solvent, the residue resins or rubbers remain in the device as a concentrated residue. Typically, the residue is removed from the device by gravity flow through a drain typically into a disposal drum. To maintain fluidity of the concentrated residue, a certain amount of photopolymer solvent typically remains in the residue, otherwise the resins or rubbers will coalesce into an amorphous solid within the device. Unfortunately, it is known that on occasions the drain has been improperly opened to permit the residue to uncontainably flow out of the still. This is undesirable because it is both time-consuming and costly to remove the spill and exposes an operator to the chemicals comprising the waste photopolymer fluid. Further, it has been discovered that the concentrated residue has a flash point temperature between 100xc2x0 F. and 140xc2x0 F., defining the residue as Class 11 liquid in accordance with 29 CFR 1910.106(a)(18)(i). Not only is the residue a potential fire hazard, particularly as the residue is drained from the device at an elevated temperature, its disposal is subject to special handling requirements.
In the photopolymer solvent recovery industry, recent innovations have been primarily directed to maintaining residue fluidity while attempting to maximize solvent recovery. However, very little attention has been given to the prevention of residue spills.
In our pending U.S. patent application Ser. No. 09/151,222 filed Sep. 10, 1998, entitled Modular Solvent Recovery Device, a modular solvent recovery device has a still and a drum cavity positioned thereunder which is sized to receive a drum. Concentrated residue discharged from the still flows into the drum for appropriate handling and disposal. The drum cavity has a floor with two side walls and a back wall extending upwardly therefrom. Pivotally mounted to a frame is a cavity door which removably engages the floor and the side walls. A gasket is removably mounted to the cavity door to assist in creating a seal between the cavity door and the floor and side walls. The cavity door has sufficient height to contain and hold the contents of the still in the event of an undesired spill. However, the drum must be manually inserted and removed from the drum cavity. When the drum is filled with residue, it is difficult to move due to its weight and the confined space of the drum cavity. Further, there is risk of a spill during the removal operation because it is difficult to place a lid onto the drum while in the drum cavity. Although other known solvent distillation devices have a drum opening, such openings simply permit the disposition of the drum in a position to receive waste discharged from the device and lack the containment capability of the drum cavity described above. Spills occurring in the opening can flow out of the device, requiring expensive and hazardous cleanup operations.
Thus, there remains a need for a containment cart which can receive and hold the contents of the still in the event the drain is improperly opened and which assists in the insertion and removal of the drum into and from, respectfully, the drum cavity or opening. Accordingly, it is to the provision of a containment cart for a solvent recovery system that meets these needs that the present invention is primarily directed.
This invention overcomes the disadvantages of the prior art by providing a containment cart utilized to contain liquid spills within or from a solvent recovery device. The containment cart has a floor, two side walls, and a rear wall between the side walls. Wheels are mounted to the floor, allowing the containment cart to be readily transportable and insertable into a drum cavity of a solvent recovery device. Caster wheels assist an operator in changing direction of the cart. A releasable and sealable door acts as a ramp once lowered. Further, while lowered, the door raises the front wheels to prevent the cart from undesired movement while drums are being placed on or removed from the cart. A channel is disposed along a front face of the side walls and floor of the cart to receive a gasket. The door has a mating protrusion extending outwardly from the door to extend into the channel and sealably engage the gasket while the door operably engages the front face.